Two of the most dangerous substances to biological macromolecules are the same as those essential for life—oxygen and glucose.
Various harmful forms of oxygen are generated in the body; singlet oxygen, superoxide radicals, hydrogen peroxide, and hydroxyl radicals all cause tissue damage. A catchall term for these and similar oxygen related species is “reactive oxygen species” (ROS). ROS damage tissue proteins, lipids, and nucleic acids (DNA) and are endpoints of many chronic and acute diseases such as cancer, atherosclerosis, diabetes, aging, rheumatoid arthritis, dementia, trauma, stroke, and infection.
ROS are also generated from glucose. One mechanism is through the formation of cytotoxic carbonyls, such as methylglyoxal (MG) and 3-deoxyglucosome (3DG) that are known precursors to the formation of Advanced Glycation End Products (AGEs).
An extremely important consequence of AGEs is their binding to receptors on many different types of cells. The best-known receptor is RAGE, which belongs to the immunoglobulin superfamily. The internalization of AGEs by their receptors lead to increased production of ROS in the cell and increases in cytokine, endothelium, thrombomodulin and other inflammatory factors. It should be noted that the number of RAGE receptors are increased in hyperglycemia.
Recently, it has been demonstrated that the inhibition of AGE formation reduced the extent of nephropathy in diabetic rats [Ninomiya, T., et al., EF6555, A novel AGE production inhibitor, prevents progression of diabetic nephropathy in STZ-induced rats. (Abstract). Diabetes, 2001. 50 Suppl. (2): p. A178-179.]. Therefore, substances that reduce AGE formation, such as inhibitors of 3DG, should limit the progression of disease and may offer new tools for therapeutic interventions [Bierhaus, A., et al., AGEs and their interaction with AGE-receptors in vascular disease and diabetes mellitus. I. The AGE concept. Cardiovasc Res, 1998. 37(3): p. 586-600], [Thornalley, P. J., Advanced glycation and the development of diabetic complications. Unifying the involvement of glucose, methylglyoxal and oxidative stress. Endocrinol. Metab., 1996. 3: p. 149-166.].
MG production is the result of a mistake in glycolysis and, as such, cannot be controlled therapeutically. The body removes most MG via the glyoxylase pathway, which requires glutathione, a compound that also protects cells from ROS by direct interaction with ROS species. 3DG escapes detoxification by the glyoxylase pathway but is converted to 3-deoxyfructose, an inert metabolite by aldehyde reductase; however, 3DG can also compromise the activity of this enzyme.
Dynamis Therapeutics has developed several proprietary compounds that can regulate the concentration of 3-deoxyglusocone in vivo. Since 3DG induces the formation of AGEs, which induce ROS, and directly inactivates at least two key enzymes responsible for the regeneration of glutathione, an important antioxidant, Dynamis expects that compounds that inhibit the formation of 3DG should be effective treatments for diseases associated with ROS.
The schematic set forth in FIG. 18 describes the various disease states affected by ROS.
3DG has many toxic effects on cells and is present at elevated concentrations in several disease states. Some of the harmful effects of 3DG are as follows:
3DG induces reactive oxygen species, which results in oxidative DNA damage [Shimoi, K., et al., Oxidative DNA damage induced by high glucose and its suppression in human umbilical vein endothelial cells. Mutat Res, 2001. 480-481: p. 371-8]                3DG inactivates some of the most important enzymes that protect cells from ROS. For example, glutathione peroxidase, a central antioxidant enzyme that uses glutathione to remove ROS, and glutathione reductase, which regenerates glutathione, are both inactivated by 3DG. [Vander Jagt, D. L., et al., Inactivation of glutathione reductase by 4-hydroxynonenal and other endogenous aldehydes. Biochem Pharmacol, 1997. 53(8): p. 1133-40], [Niwa, T. and S. Tsukushi, 3-deoxyglucosone and AGEs in uremic complications: inactivation of glutathione peroxidase by 3-deoxyglucosone. Kidney Int Suppl, 2001. 78: p. S37-41].        3DG inactivates aldehyde reductase [Takahashi, M., et al., In vivo glycation of aldehyde reductase, a major 3-deoxyglucosone reducing enzyme: identification of glycation sites. Biochemistry, 1995. 34(4): p. 1433-8]. This is important, since aldehyde reductase is the cellular enzyme that protects the body from 3DG. Dynamis has supportive evidence that this detoxification of 3DG to 3-deoxyfructose (3DF) is impaired in diabetic humans since their ratio of urinary and plasma 3DG to 3DF differs significantly from non-diabetic individuals. [Lal, S., et al., Quantitation of 3-deoxyglucosone levels in human plasma. Arch Biochem Biophys, 1997. 342(2): p. 254-60.        3DG induced reactive oxygen species contribute to the development of diabetic complications. [Araki, A., [Oxidative stress and diabetes mellitus: a possible role of alpha-dicarbonyl compounds in free radical formation]. Nippon Ronen Igakkai Zasshi, 1997. 34(9): p. 716-20.]. Specifically, 3DG induces heparin-binding epidermal growth factor, a smooth muscle mitogen that is abundant in atherosclerotic plaques. This suggests that an increase in 3DG may trigger atherogenesis in diabetes. [Taniguchi, N., et al., Involvement of glycation and oxidative stress in diabetic macroangiopathy. Diabetes, 1996. 45 Suppl 3: p. S81-3.], [Che, W., et al., Selective induction of heparin-binding epidermal growth factor-like growth factor by methylglyoxal and 3-deoxyglucosone in rat aortic smooth muscle cells. The involvement of reactive oxygen species formation and a possible implication for atherogenesis in diabetes. J Biol Chem, 1997. 272(29): p. 18453-9].        3DG is a teratogenic factor in diabetic embryopathy leading to embryo malformation [Eriksson, U. J., et al., Teratogenicity of 3-deoxyglucosone and diabetic embryopathy. Diabetes, 1998. 47(12): p. 1960-6.]. This appears to arise from 3DG accumulation, which leads to superoxide-mediated embryopathy.        3DG induces apoptosis in macrophage-derived cell lines [Okado, A., et al., Induction of apoptotic cell death by methylglyoxal and 3-deoxyglucosone in macrophage-derived cell lines. Biochem Biophys Res Commun, 1996. 225(1): p. 219-24] and is toxic to cultured cortical neurons [Kikuchi, S., et al., Neurotoxicity of methylglyoxal and 3-deoxyglucosone on cultured cortical neurons: synergism between glycation and oxidative stress, possibly involved in neurodegenerative diseases. J Neurosci Res, 1999. 57(2): p. 280-9] and PC12 cells [Suzuki, K., et al., Overexpression of aldehyde reductase protects PC12 cells from the cytotoxicity of methylglyoxal or 3-deoxyglucosone. J Biochem (Tokyo), 1998. 123(2): p. 353-7]. A recent study on the cause of amyotropic lateral sclerosis, a form of motor neuron disease, has suggested that accumulation of 3DG can lead to neurotoxicity as a result of ROS generation [Shinpo, K., et al., Selective vulnerability of spinal motor neurons to reactive dicarbonyl compounds, intermediate products of glycation, in vitro: implication of inefficient glutathione system in spinal motor neurons. Brain Res, 2000. 861(1): p. 151-9].        AGEs have specific receptors on cells called RAGE. The activation of cellular RAGE on endothelium, mononuclear phagocytes, and lymphocytes triggers the generation of free radicals and the expression of inflammatory gene mediators [Hofmann, M. A., et al., RAGE mediates a novel proinflammatory axis: a central cell surface receptor for S100/calgranulin polypeptides. Cell, 1999. 97(7): p. 889-901]. This increased oxidative stress leads to the activation of the transcription factor NF-kB and promotes the expression of NF-kB genes that have been associated with atherosclerosis [Bierhaus, A., et al., AGEs and their interaction with AGE-receptors in vascular disease and diabetes mellitus. I. The AGE concept. Cardiovasc Res, 1998. 37(3): p. 586-600].        In relationship to cancer, blockage of RAGE activation inhibits several mechanisms linked to tumor proliferation and trans-endothelial migration of tumor cells. This also decreases growth and metastases of both spontaneous and implanted tumors [Taguchi, A., et al., Blockade of RAGE-amphoterin signalling oppresses tumour growth and metastases. Nature, 2000. 405(6784): p. 354-60].        
Oxygen
Various harmful forms of oxygen are generated in the body: singlet oxygen; superoxide radicals; hydrogen peroxide; and hydroxyl radicals all cause tissue damage. A catchall term for these and similar oxygen related species is reactive oxygen species (ROS). ROS damage, among other things, tissue proteins, lipids, and nucleic acids (e.g., DNA), and are endpoints of many chronic and acute diseases such as cancer, atherosclerosis, diabetes, aging, rheumatoid arthritis, dementia, trauma, stroke, and infection.
Glucose
Although glucose is the most important fuel for life, it also forms cytotoxic carbonyls, such as methylglyoxal (MG) and 3-deoxyglucosome (3DG), which lead to ROS. MG production is the result of a mistake in glycolysis and, as such, cannot be controlled therapeutically. The body removes most MG via the glyoxylase pathway, which requires glutathione, a compound that also protects cells from ROS by direct interaction with ROS species. Although, 3DG escapes detoxification by the glyoxylase pathway, its levels can be controlled since it arises from a non-essential enzymatic reaction which can be inhibited. Previously, this enzyme was isolated and characterized and has been termed “Amadorase”.
AGEs
In addition to forming ROS, 3DG is a precursor to Advanced Glycation End Products (AGEs), which also have deleterious effects on the body and are involved in many inflammatory diseases. Non-enzymatic glycation of protein, in which reducing sugars are covalently attached to free amino groups of protein and ultimately form AGEs, has been found to occur during normal aging and at accelerated rate in diabetes mellitus (Bierhaus et al., 1998, Cardiovasc. Res. 37:586-600). Protein glycation is the first step in a cascade of reactions that lead to reactive bifunctional compounds such as methylglyoxal and 3DG that lead to formation of AGEs.
Enhanced formation and accumulation of AGEs has also been proposed to play a major role in the pathogenesis in additional diseases such as atherosclerosis and Alzheimer's disease since AGE formation and protein crosslinks are irreversible processes that alter the structural and functional properties of proteins, lipid components, and nucleic acids. Id.
An extremely important indirect consequence of AGEs is their binding to receptors on many different types of cells. The best-known receptor is RAGE, which belongs to the immunoglobulin superfamily. The internalization of AGEs by their receptors lead to increased production of ROS in the cell and increases in cytokine, endothelium, thrombomodulin and other inflammatory factors. It should be noted that the number of RAGE receptors are increased in hyperglycemia.
Recently, it has been demonstrated that the inhibition of AGE formation reduced the extent of nephropathy in diabetic rats (Ninomiya et al., 2001, Diabetes 50:A178-A179). Therefore, substances that reduce AGE formation, such as inhibitors of 3DG, should limit the progression of disease and may offer new tools for therapeutic interventions (Bierhaus et al.; Thornalley, 1996, Endonicrol. Metab. 3:149-166). Without wishing to be bound by any particular theory, the schematic set forth as FIG. 17 depicts the various disease states affected by ROS.
3-Deoxyglucosone is a Potent Protein Glycating Agent Associated with Protein Crosslinking
3-deoxyglucosone (3DG) is a 1,2-dicarbonyl-3-deoxysugar which is a potent protein crosslinker, is teratogenic and/or mutagenic, causes apoptosis, mutations, and formation of active oxygen species, and is a precursor to the formation of Advanced Glycation End product (AGE) modified proteins. As reviewed by Brownlee and shown in FIG. 1, the previously generally accepted pathway for formation of 3DG comprises a reversible reaction between glucose and the ε-NH2 groups of lysine-containing proteins, forming a Schiff base (Brownlee et al., 1994, Diabetes 43:836-841). This Schiff base then rearranges to form a more stable ketoamine known as fructose-lysine (FL) or the “Amadori product”. The dogma has been that 3DG production resulted exclusively from subsequent non-enzymatic rearrangement, dehydration, and fragmentation of the fructoselysine containing protein (Brownlee et al., 1994, Diabetes 43:836-841; Makita et al., 1992, Science 258:651-653) (see FIG. 1). However, more recent work has shown that an enzymatic pathway for the production of 3DG exists as well (see FIGS. 1 and 2 and Brown et al., U.S. Pat. No. 6,004,958). The disclosure provided by Brown et al (U.S. Pat. No. 6,006,958) is incorporated by references as in recited in its entirety herein.
A metabolic pathway was discovered which produces relatively high concentrations of 3DG in organs affected by diabetes (Brown et al., U.S. Pat. No. 6,004,958). It was also found that a specific kinase converts fructose-lysine into fructose-lysine-3-phosphate (FL3P) in an ATP dependent reaction, and that FL3P then breaks down to form free lysine, inorganic phosphate, and 3DG. Id. Methods have also been described for assessing diabetic risk, based on measuring components of the 3DG pathway (International Publication No. WO 99/64561).
Brown et al., U.S. Pat. No. 6,004,958, describe a class of compounds which inhibit the enzymatic conversion of fructose-lysine to FL3P and inhibit thereby formation of 3DG. Specific compounds which are representative of the class have also been described (Brown et al., International Publication No. WO 98/33492). For example, it was found that urinary or plasma 3DG can be reduced by meglumine, sorbitollysine, mannitollysine, and galactitollysine. Id. It was also found that diets high in glycated protein are harmful to the kidney and cause a decrease in birth rate. Id. It has also been disclosed that the fructose-lysine pathway is involved in kidney carcinogenesis. Id. Further, previous studies demonstrate that diet and 3DG can play a role in carcinogenesis associated with this pathway (see International Publication Nos. WO 00/24405; WO 00/62626; WO 98/33492).
Detoxification of 3DG
3DG can be detoxified in the body by at least two pathways. In one pathway, 3DG is reduced to 3-deoxyfructose (3DF) by aldehyde reductase, and the 3DF is then efficiently excreted in urine (Takahashi et al., 1995, Biochemistry 34:1433). Another detoxification reaction oxidizes 3DG to 3-deoxy-2-ketogluconic acid (DGA) by oxoaldehyde dehydrogenase (Fujii et al., 1995, Biochem. Biophys. Res. Comm. 210:852).
Results of studies to date show that the efficiency of at least one of these enzymes, aldehyde reductase, is adversely affected in diabetes. When isolated from diabetic rat liver, this enzyme is glycated on lysine at positions 67, 84 and 140 and has a low catalytic efficiency when compared with the normal, unmodified enzyme (Takahashi et al., 1995, Biochemistry 34:1433). Since diabetic patients have higher ratios of glycated proteins than normoglycemic individuals they are likely to have both higher levels of 3DG and a reduced ability to detoxify this reactive molecule by reduction to 3DF. It has also been found that overexpression of aldehyde reductase protects PC12 cells from the cytotoxic effects of methylglyoxal or 3DG (Suzuki et al., 1998, J. Biochem. 123:353-357).
The mechanism by which aldehyde reductase works has been studied. These studies demonstrated that this important detoxification enzyme is inhibited by aldose reductase inhibitors (ARIs) (Barski et al., 1995, Biochemistry 34:11264). ARIs are currently under clinical investigation for their potential to reduce diabetic complications. These compounds, as a class, have shown some effect on short term diabetic complications. However, they lack clinical effect on long term diabetic complications and they worsen kidney function in rats fed a high protein diet. This finding is consistent with the newly discovered metabolic pathway for lysine recovery.
Aminoguanidine, an agent which detoxifies 3DG pharmacologically via formation of rapidly excreted covalent derivatives (Hirsch et al., 1992, Carbohydr. Res. 232:125-130), has been shown to reduce AGE-associated retinal, neural, arterial, and renal pathologies in animal models (Brownlee et al., 1994, Diabetes 43:836-841; Brownlee et al., 1986, Science 232:1629-1632; Ellis et al., 1991, Metabolism 40:1016-1019; Soulis-Liparota et al., 1991, Diabetes 40:1328-1334; and Edelstein et al., 1992, Diabetologia 35:96-97).
Role of 3DG in Diabetes and Other Diseases
Past studies have concentrated on the role of 3DG in diabetes. It has been demonstrated that diabetic humans have detectably elevated levels of 3DG and 3-deoxyfructose (3DF), 3DG's detoxification product, in plasma (Niwa et al., 1993, Biochem. Biophys. Res. Commun. 196:837-843; Wells-Knecht et al., 1994, Diabetes. 43:1152-1156) and in urine (Wells-Knecht et al., 1994, Diabetes. 43:1152-1156), as compared with non-diabetic individuals. Furthermore, diabetics with nephropathy were found to have elevated plasma levels of 3DG compared to non-diabetics (Niwa et al., 1993, Biochem. Biophys. Res. Commun. 196:837-843).
A recent study comparing patients with insulin-dependent diabetes mellitus (IDDM) and noninsulin-dependent diabetes mellitus (NIDDM) confirmed that 3DG and 3DF levels were elevated in blood and urine from both types of patient populations (Lal et al., 1995, Arch. Biochem. Biophys. 318:191-199). It has even been shown that incubation of glucose and proteins in vitro under physiological conditions produces 3DG.
In turn, it has been demonstrated that 3DG glycates and crosslinks protein creating detectable AGE products (Baynes et al., 1984, Methods Enzymol. 106:88-98; Dyeret al., 1991, J. Biol. Chem. 266:11654-11660).
The normal pathway for reductive detoxification of 3DG (conversion to 3DF) may be impaired in diabetic humans since their ratio of urinary and plasma 3DG to 3DF differs significantly from non-diabetic individuals (Lal et al., 1995, Arch Biochem. Biophys. 318:191-199).
Furthermore, elevated levels of 3DG-modified proteins have been found in diabetic rat kidneys compared to control rat kidneys (Niwa et al., 1997, J. Clin. Invest. 99:1272-1280). It has been demonstrated that 3DG has the ability to inactivate enzymes such as glutathione reductase, a central antioxidant enzyme. It has also been shown that hemoglobin-AGE levels are elevated in diabetic individuals (Makita et al., 1992, Science 258:651-653) and other AGE proteins have been shown in experimental models to accumulate with time, increasing from 5-50 fold over periods of 5-20 weeks in the retina, lens and renal cortex of diabetic rats (Brownlee et al., 1994, Diabetes 43:836-841). In addition, it has been demonstrated that 3DG is a teratogenic factor in diabetic embryopathy (Eriksson et al., 1998, Diabetes 47:1960-1966).
Nonenzymatic glycation, in which reducing sugars are covalently attached to free amino groups and ultimately form AGEs, has been found to occur during normal aging and to occur at an accelerated rate in diabetes mellitus (Bierhaus et al., 1998, Cardiovasc. Res. 37:586-600). Crosslinking of proteins and the subsequent AGE formation are irreversible processes that alter the structural and functional properties of proteins, lipid components, and nucleic acids (Bierhaus et al., 1998, Cardiovasc. Res. 37:586-600). These processes have been postulated to contribute to the development of a range of diabetic complications including nephropathy, retinopathy, and neuropathy (Rahbar et al., 1999, Biochem. Biophys. Res. Commun. 262:651-660).
Recently, it has been demonstrated that inhibition of AGE formation reduced the extent of nephropathy in diabetic rats (Ninomiya et al., 2001, Diabetes 50:178-179). Therefore, substances which inhibit AGE formation and/or oxidative stress appear to limit the progression of diabetes and its complications and may offer new tools for therapeutic interventions in the therapy of diabetes (Bierhaus et al., 1998, Cardiovasc. Res. 37:586-600; Thomalley, 1996, Endocrinol. Metab. 3:149-166).
In sum, 3DG has numerous toxic effects on cells and is present in elevated levels in several disease states. The harmful effects of 3DG include, but are not limited to, the following.
It is known that 3DG induces reactive oxygen species in human umbilical vein endothelial cells, which results in oxidative DNA damage (Shimoi, 2001, Mutat. Res. 480:371-378).
It was previously demonstrated that 3DG inactivates some of the most important enzymes that protect cells from ROS. For example, glutathione peroxidase, a central antioxidant enzyme, and glutathione reductase, which are required to regenerate glutathione in cells, are both inactivated by 3DG (Vander Jagt, 1997, Biochem. Pharmacol. 53:1133-1140; Niwa et al., 2001, Kidney Int. Suppl. 78:S37-S41) Prior studies indicate that 3DG inactivates aldehyde reductase (Takahashi et al., 1995, Biochemistry 34:1433-1438). This is important, since aldehyde reductase is the cellular enzyme that protects the body from 3DG. Dynamis has supportive evidence that this detoxification of 3DG to 3-deoxyfructose (3DF) is impaired in diabetic humans since their ratio of urinary and plasma 3DG to 3DF differs significantly from non-diabetic individuals (Lal et al., 1997, Arch. Biochem. Biophys. 342:254-260).
Additionally, it has been demonstrated that 3DG induced reactive oxygen species contribute to the development of diabetic complications (Araki, 1997, Nippon Ronen Igakkai Zasshi 34:716-720). Specifically, 3DG induces heparin-binding epidermal growth factor, a smooth muscle mitogen that is abundant in atherosclerotic plaques. This suggests that an increase in 3DG may trigger atherogenesis in diabetes (Taniguchi et al., 1996, Diabetes 45(Supp. 3):S81-S83; Che et al., 1997, J. Biol. Chem. 272:18453-18459).
Further, 3DG is a known teratogenic factor in diabetic embryopathy leading to embryo malformation (Eriksson et al., 1998, Diabetes 47:1960-1966). This appears to arise from 3DG accumulation, which leads to superoxide-mediated embryopathy.
More recently, it was demonstrated that 3DG induces apoptosis in macrophage-derived cell lines (Okado et al., 1996, Bichem. Biophys. Res. Commun. 225:219-224), and is toxic to cultured cortical neurons (Kikuchi et al., 1999, J. Neurosci. Res. 57:280-289) and PC12 cells (Suzuki et al., 1998, J. Biochem. (Tokyo) 123:353-357). A recent study on the cause of amyotropic lateral sclerosis, a form of motor neuron disease, has suggested that accumulation of 3DG can lead to neurotoxicity as a result of ROS generation (Shinpo et al., 2000, Brain Res. 861:151-159).
Previous studies demonstarted that 3DG glycates and crosslinks protein leading to a complex mixture of compounds called advanced glycation end products (AGEs) (Baynes et al., Methods Enzymol. 106:88-98; Dyer et al., 1991, J. Biol. Chem. 266:11654-11660). AGEs have been implicated in most inflammatory diseases such as diabetes, atherosclerosis and dementia. They are most commonly formed on long-lived structural proteins such as collagen.
Hemoglobin-AGE levels are elevated in diabetic individuals (Makita et al., 1992, Science 258:651-653), and other AGE proteins have been shown in experimental models to accumulate with time, increasing from 5-50 fold over periods of 5-20 weeks in the retina, lens and renal cortex of diabetic rats (Brownlee et al., 1994, Diabetes 43:836-841).
AGEs have specific receptors on cells called RAGE. The activation of cellular RAGE on endothelium, mononuclear phagocytes, and lymphocytes triggers the generation of free radicals and the expression of inflammatory gene mediators (Hofmann et al., 1999, Cell 97:889-901). This increased oxidative stress leads to the activation of the transcription factor NF-kB and promotes the expression of NF-kB genes that have been associated with atherosclerosis (Bierhaus et al.).
In relationship to cancer, blockage of RAGE activation inhibits several mechanisms linked to tumor proliferation and trans-endothelial migration of tumor cells. This also decreases growth and metastases of both spontaneous and implanted tumors (Taguchi et al., 2000, Nature 405:354-360).
Increasing the kidney concentration of 3DG in a rat model of renal cell carcinoma increased the rate of formation tumors and increased the total number of tumors 3-fold.
High concentrations of 3DG are present in human lymphomas and in retinoblastoma and neuroblastoma cells. Since many tumors synthesize ROS at an elevated rate and appear to be under persistent oxidative stress, 3DG or 3DG derived AGEs may be involved.
Diabetic humans have elevated levels of 3DG and 3DF in plasma (Niwa et al., 1993, Biochem. Biophys. Res. Commun. 196:837-843; Wells-Knecht et al., 1994, Diabetes 43:1152-1156) and urine (Wells-Knecht et al.), as compared with non-diabetic individuals.
Diabetics with nephropathy were found to have elevated plasma levels of 3DG compared with other diabetics (Niwa et al., 1993, Biochem. Biophys. Res. Commun. 196:837-843). Elevated levels of 3DG-modified proteins are found in diabetic versus control rat kidneys (Niwa et al., 1997, J. Clin. Invest. 99:1272-1280).
Skin
Human skin is a composite material comprising a superficial component, the epidermis, and a deep component, the dermis. The outermost layer of the epidermis is the stratum corneum. This layer is the stiffest layer of the skin, as well as the one most affected by the surrounding environment. Deep to the stratum corneum is the internal portion of the epidermis. Deep to the epidermis, is the papillary layer of the dermis, which comprises relatively loose connective tissue which defines the micro-relief of the skin. The reticular dermis, deep to the papillary dermis, is dense connective tissue that is spatially organized. The reticular dermis is also associated with coarse wrinkles. Deep to the dermis is subcutaneous connective tissue and adipose tissue.
The principal functions of the skin include protection, excretion, secretion, absorption, thermoregulation, pigmentogenesis, accumulation, sensory perception, and regulation of immunological processes. These functions are detrimentally affected by the structural changes in the skin due to aging and various diseases and disorders of the skin. The physiological changes associated with normal skin aging and photoaging include loss of elasticity, decreased collagen, collagen and elastin crosslinking, wrinkling, dry/rough texture, and mottled hyperpigmentation, for example.
The mechanical properties of the skin, such as elasticity, are controlled by the density of the network of collagen and elastic fibers coursing throughout. Damaged collagen and elastin proteins lose their contractile properties, resulting in such things as skin wrinkling and skin surface roughness. As skin ages or begins to deteriorate due to a disease or disorder, it acquires sags, stretch marks, bumps, or wrinkles, it roughens, it can become discolored, and it has reduced ability to synthesize vitamin D. Aged skin also becomes thinner and has a flattened dermoepidermal interface because of the alterations of collagen, elastin, and glycosaminoglycans.
The skin is a crucial organ and many disorders, diseases and conditions related to skin remain without effective therapeutics and/or diagnostics. Despite the fact that skin aging, wrinkling, and the like, are the subject of intense research, there remains a long felt need in the art for the development of new methods to treat these and other diseases, disorders or conditions relating to the skin. The present invention meets this need.